Fbiedbich schatfeer



F. SCHAFFER.

METHOD 0F MAKING RAILWAY DISK WHEELS.

APPLICATION mso MAmzs. |916.

PatentedSept. 27, 1921.

UNITED STATES OFFICE.

METHOD OIE' MAKING RAIL'WAY DISK WHEELS.

Specification of Letters Patent.

Patented Sept. 27, 1921.

Application filed March 28, 1916. Serial No. 87,146.

(GRANTED UNDER THE PROVISIONS 0F THE ACT 0F MARGH 3, 1921, 41 STAT. Il., 1313.)

To all 'whom t may concern:

Be it known that I, FRIEDRICH SCHAFFER, manager, a subject of the Emperor of Austria, residing at Leobersdorf, near Vienna, in the Empire of Austria, have invented certain new and useful Improvements in Methods of Making Railway Disk Wheels, (for which I filed applications in Germany, $548,987, Aug, as, 1915; #49421, oct. i, 1915, and Feb. 23, 1916,) of which the following is a specification. f

The kind of steel employed for the manufacture of railway-wheels ought to have, generally speaking, in addition to great strength and elongation, a great resistance against shock and wear. But even when Athese properties are secured'by a certain heat treatment, there will still be required a certain stability in the structure of the steel which must be maintained in spite of the heat continuously generated by thel braking.

A comparison of the carbon steel, commonly used for, the making of `railwaywheels, vwith therwell-known toughened manganese steel (which latter contains about 1% of carbon and 12% of manganese), will clearly show that the last-mentioned kind of steel is far more suitable for the making of railway-wheels, than the first-named.

`For,`besides possessing important mechanical properties, manganese steel has an incomparably greater power of resistance against wear than the common carbonsteel.

However, in spite of the fact that the aforesaid properties render the kind of manganese steel," containing about 1% carbon and 12% manganese more suitable for the making of railway-wheels than vany other kind of steel, it yet should be remembered that the said kind of manganese steel possesses properties which render it unfit for the manufacture of, and use in railway wheels of the disk type.

When manganese steel is heated for a prolonged period of `time at a`relatively low temperature, or,what would amount to the same thing, `when this steel Ais repeatedly heated even at a lower temperature, such as will occur when the brakes are applied, it will be found that the structure of the steel changes, resulting in a deterioration of its quality.

I have, however, discovered that a steel containing about 1% carbon and 17%, or more, manganese, may be toughened by a suitable heat treatment, and that such a steel in addition to the properties of manganese steel referred to, possesses a far superior` stability in structure.

I also have found that this steel, which contains either 17% manganese, or more, may be toughened in a different, and a more advantageous manner, than the steel containing about 12% manganese.

As is well known, the last-mentioned kind of steel is toughened by being heated to a certain temperature after which it is rapidly quenched in water, or in oil, the latter method however not yielding quite as satis1 factory results.

In order to toughen steel containing 17% manganese, or more, so as to secure the best possible results, the steel must be heated to the proper temperature, e. g. between 1000o and11 00o C. and then simply cooled in the open air.

The entire toughening operation, however, is also successfully carried out, if the steel having first been properly heated is permitted to cool moderately faster than if the cooling were effected solely in the calm open air.

It follows that the toughening of the steel will be rendered equally edective, if for that purpose a hardening liquid, or a current of air, or both are applied.

,The advantages resulting from the employment of a steel for the making of railway disk-wheels containing about 1% carbon and 17%, or more, manganese, as against the use of a steel containing about 1% carbon and 12% manganese are as follows:

a. The heat generated due to the frequent braking of the wheel, will but imperceptibly affect the structure of the toughened metal, hence the total of mechanical qualities obtained by the heat treatment or the. toughening process, will not 'be perceptibly altered.

Z). If the railway-wheel is cast, forged, rolled or shaped by any desired method into a disk-wheel, z'. c., into a wheel in which the rim, the disk and the hub portions are all made in one piece, from one solid block of steel, it will be found that such a wheel cannot be toughened in the ordinary way by first being heated and then quenched in water. The explanation for this is, that when the wheel is quickly cooled in the quenchingbath, the disk portion, being thin and having a large cooling surface, will shrink so much faster than the rim portion, that in the wheel big strains will be set up and the wheel will crack. In manganese steel such strains are promoted because, owing to the peculiar property of the manganese steel, the amount of its shrinkage is greater than in most ofthe other kinds of steel.

However, when a manganese steel is employed containing about 1% carbon and 17% manganese or more, it will be obvious from what has been stated above that the toughening process need not be quickly carried by way of quenching, but that it can be extended over a much longer period, e'. e., over a period of suflicientduration as to afford to the various parts of the wheel the rim, the disk and the hub an opportunity to be cooled with the varying degree required by the `quantity of heat stored up therein as also by the area of cooling surface to each part. Y

Thus for instance, during the whole time required for the cooling of the wheel, the maximum degree of cooling ought to be applied to the rim, less degree to the hub, and the minimum degree to the disk.

The quantity of the cooling medium, whether a liquider a gas, or both, must be governed by and applied in corresponding proportions to the said three parts. By working alongthese lines, one can, throughout the entire cooling process and at every individual stage thereof, secure a temperature which will practically prove to be one andthe same in every part of the wheel. The result obtained by this improved method is the absence of any strains in .the wheel, so that the metalstructure will be the same in the rim, the disk and the hub.`

In the accompanying drawing is shown in a vertical section by way of example, a device adaptedto carry out the special and improved method of'cooling according to my invention and which constitutes a part of theJ heat treatment.

In this drawing:

1 indicates a circular tank, having an inlet 2 and an outlet 3. In the interior of the tank 1 there is-provided a funnel 4, having a sieveV 5 and anY inlet 6. On the edge of the funnel/1 is placed the wheel after having been suitably heated. VAbove the wheel is e arranged a funnel 7`With a sieve 8, and having an inlet 9. Passing through the-center of the hubof the wheel is a sieve 10, provided Vwith an inlet 11 and projecting toward an outlet 12. Aswill be readily understood the object ofthe tank 1 is to cool the rimV of the wheel, while the disk portion thereof is cooled through the sieves 5 Yand 8, and the hub part by aid of the sieve 10. The parts 7, 8, 9, 10 and 11 as a whole are movable to and away from the wheel by means of pipe hinges 14. The parts can be moved in the direction of the arrow 13 to provide room for the insertion and removal of the wheel.

The inlets 2, 6, 9 and 11 as well as the outlets 3 and 12 are each provided with a regulating device to enable the quantity of the cooling medium which passes through to be controlled according to requirement. By the proper regulation of the cooling medium, the surplus of heat will be conducted away from every portion of the wheel in such a manner that the decrease in temperature will be the same at every point of the wheel, so that no strain whatsoever can arise therein and the structure or the metal will remain undisturbed. However, the same obj ect may obviously be attained in many other ways and by means of other kinds of devices.

It is also understood that the cooling by means of various quantities of a cooling medium, applied to the different parts of the wheel per second, may also gradually be effected, z'. e., by the division of the cooling operation into a number of successive stages; each stage consisting of a cooling operation effected by the cooling medium and followed by an interval during which no cooling occurs, but during which an opportunity is afforded to the wheel to equalize any slight differences of temperature that may have arisen and thereby render the temperature uniform at every point of the wheel.

In this manner no strain whatsoever can possibly arise in the material.

What I claim is:

1. The process of making railway-wheels of the disk-type of steel containing a comparatively large percentage of manganese, which process consists in first subjecting the wheel to a suitable heat treatment, and then cooling the wheel by subjecting the rim of the wheel to the maximum cooling effect, the hub to a lesser cooling effect and the disk portion to the minimum cooling effect but cooling the parts more slowly than they would be cooled when quenched.

2. The process of making railway-wheels of the disk-type of steel containing a comparatively large percentage of manganese, which process consists in first subjecting the wheel to a suitable heat treatment, and then cooling the wheel by the aid of fluid media, at the same time regulating the quantities of these cooling media in such a way that the largest cooling effect is produced in the rim of the wheel, a correspondingly smaller cooling effect in the hub and the smallest cooling effect in the disk portion.

3. The recess of making railway-wheels of the dis -type of steel containing a comparatively large percentage of manganese, which process consists in first subjecting the wheel to a suitable heat treatment, and then cooling the wheel by subjecting its rim to the maximum cooling effect, the hub to a correspondingly lesser cooling effect and the disk portion to the minimum cooling effect, the cooling operation being divided into stages, each stage consistingof a separate cooling operation followed by an interval during which no cooling occurs to allow for equalization of slight differences of heat in the various parts of the wheel.

4f. The process of making railway wheels of the disk type, which process consists in employing a steel containing about 1% of carbon and 17% or more of manganese, subjecting the said wheel to a suitable heating operation and then cooling the wheel by aid of suitable media, and at the same time regulating the said cooling media in such a manner that the largest cooling effect will be produced in the rim of the wheel, a correspondingly smaller cooling effect in the hub and the smallest cooling effect in the disk portion, according to the amount of material contained in the several parts of the wheel, that is to say, according to the amount of heat stored up and the extent of applied to the several portions of the wheel will be proportionate to the mass of said portions, that is to say, according to the amount of heat stored up in each portion of the wheel, and the extent of the cooling surface of said portion, the entire cooling operation being divided into stages, each stage consisting of a separate cooling operation followed by an interval during which no cooling occurs.

In testimony whereof I have hereunto set I my hand in presence of two subscribing witnesses.

FRIEDRICH SGHAFFER. Witnesses:

ARTHUR LINDnNsTEAD, AUGUST FUGGER. 

